Alan Cumming has to pee. “Keep talking!” he commands, continuing the conversation as he steps into the toilet of his dressing room on the top floor of Studio 54.

The time is drawing near for him to get into makeup and costume for the evening performance of “Cabaret,” but he doesn’t seem concerned. Earlier, he collected trash from the previous night’s “soup and booze party,” part of a postshow 23rd birthday shindig for one of the Kit Kat Boys. Cumming takes a sip from one of the plastic cups—“Oh, that’s not what I thought it was going to be”—then heaves a large Crock Pot (for cooking soup, of course) to a higher shelf.

“I like this balance of fun; it’s lovely having young energy around me,” he says. “I feel young; I’m obviously not. I do feel like Daddy. We’re really getting on. At the same time, they are just my co-workers. I think it’s nice that you can show people of that age that you can still be fun and kind—and not an asshole.”

Cumming may be the only Broadway star whose dressing room is sponsored by a liquor company (and shelves bulge with dozens of Bulldog and Skyy bottles to prove it), and he certainly doesn’t let it go to waste. “We’ve had as many as 40 people in here,” he says. “It’s like a little apartment. Doing a show gets in the way of your social life, so it’s nice to hang out in here.”

He flushes, washes his hands, and continues without missing a beat. Although it’s his star power—along with movie star Michelle Williams as Sally Bowles—that’s bringing the eager hordes to the theater to see him teasingly croon in the revival, it doesn’t mean he has a lockjaw attitude about never missing a performance. In fact, Cumming missed the previous day’s matinee due to the role for which he’s now familiar to most of America, that of Eli Gold on CBS’ “The Good Wife.” He kicked off an upfronts spectacle by taking the stage to sing “Willkommen” in character as Eli before stripping down to reveal his Emcee suspenders costume, stroking his nipples while singing amended lines that trumpeted CBS’ dominance over its TV rivals.

“I thought it was potentially utterly humiliating,” he admits. “I had to sing things like ‘Enchanté, LL Cool J,’ and things like that. But it was actually a real laugh, quite fun. It’s good to remind people—they forget and think we are just like who they see onscreen—and I’m not.” He punctuates that with one of his hiccuplike giggles.

Cumming’s ability to straddle the avant-garde and the schlocky mainstream endears him to a diverse fan base. Not only is he starring on one of America’s most addictive television shows, Cumming has edited magazines, written books—both a semiautobiographical novel and the upcoming memoir “Not My Father’s Son”—released an album, created a playful fragrance line (Cumming), and hosts late-night parties. Over the years he’s been in popcorn flicks (“Romy and Michele’s High School Reunion”), blockbusters (that X-Men franchise), and a Bond film (“GoldenEye”), along with various Web series (most recently playing himself on “The Outs”). He even had the gall to perform all the roles in a one-man version of “Macbeth” on Broadway. So why hasn’t he been derided as a pretentious pseudo-intellectual polymath with a penchant for spreading himself too thin, as has fellow Broadway actor James Franco, appearing down the street in “Of Mice and Men”?

His response is classic Cumming. “I think I don’t take myself very seriously. I do, but I have a sense of humor,” he explains. “I like my work, but I don’t take it very seriously. I really like James Franco, he’s a lovely boy. But pretension? I don’t like that word. My friend said, ‘Do not say pretentious; it’s crossing a picket line in the arts.’ And I like that.”

So where does he get his special powers to have the energy to do all of this? He’s been vegan since 2012 and still has the wiry frame of a youngster—as he proves in the skimpy “Cabaret” costumes that continue to reveal his rouged nipples.

“I have vegan powers!” he proclaims cheekily. “I have just been for an IV. No, seriously. An IV of vitamins. I really look after myself. I party like a 22-year-old as well, but I’m a sensible 22-year-old. I always drink lots of water; I take loads of vitamins. I’m very fit. I do stuff. I look at people, the kids more than half my age, and they are falling by the wayside. And I do 16 things before I come in. But I have good genes. My mother is really sprightly. I’ve always been like this. I thrive on it. I like feeling alive!”

His carpe diem attitude is the reason he’s continually described as pixielike or impish. Despite those handy monikers, however, he opted not for Puck but for that daunting one-man “Macbeth”—which seemed humanly impossible. Could he simply be an overachieving masochist?

“That was completely masochistic. But the thing about ‘Macbeth’…I love John Tiffany. Love, love him to death,” Cumming says, referring to the English director with whom he collaborated on the production. “But every time I work with him he seems to want to kill me. I’m 50, I’m going to be 50, I’m in my 50th year. I’m 49-and-a-half. I shouldn’t be doing this. But I wonder if I can still do that.”

Cumming poured himself into the production, prepared to play all the roles for its scheduled 73 performances. “I thought I could just about manage that if I lived the life of a monk,” he says. But the show was extended for two additional weeks and overlapped with “The Good Wife,” increasing his mental and physical burden. “I thought I might die.”

Despite heaps of critical praise, Cumming found his name left off the Tony nominations. (This year was different; as a previous winner for the role, Cumming was ineligible for a second Tony nomination as the Emcee.) “When I didn’t get nominated and I was on all those lists of shoo-ins I was really, obviously surprised and—oh!—disappointed,” he says. “The worst is you get pity. And you can get pity presents. People send you a nice bottle of vodka or some little thing.” The surprise snub also made Cumming reconsider why he was in the business doing the crazy things he was doing.

“I wasn’t doing it for awards, to get a Tony or whatever. And I think some people do,” he says, suddenly serious. “I realized, I’m not doing it for the audience; I’m doing it for me. I like it. I want to be able to see if I can still do it. I want to see if I can challenge myself. I want to have a good time. With ‘Macbeth,’ I wasn’t finished with it. It wasn’t out of my system. So when those things happen you say, ‘Wait a minute, don’t get all caught up in that shit.’ The thing about ‘Macbeth’—that it’s so ravishing, so difficult, so crazy—afterward, everything else is a cakewalk. I think for the rest of my career, everything will be not that difficult. That’s a great feeling. There will be challenging things, but not that challenging.”

After so much time it seemed an odd decision for him to return to a role for which he won a Tony in 1998 and defined for a 21st-century generation, but Cumming disagrees. “It felt like the right time,” he says, adding that producers wanted him to return to “Cabaret” sooner but he had turned them down. “I thought, I’d love to give it another go. It didn’t feel like going back and repeating something. It was so long ago that I didn’t remember.”

Is there some dream role or project that continues to escape him? “I’m not a yearner—in any way, in any part of my life,” he says. “I think yearnings are very overrated. I think being open, interesting things and people and experiences come to you. There’s a couple of films I’m trying to get made. But if it doesn’t happen? That’s show biz.”